Bicuspid aortic valve flow dynamics using blood speckle tracking in children

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Labatt Family Heart Centre Background Bicuspid aortic valves (BAV) are the most common form of congenital heart disease with a prevalence of up to 2%. Fusion of the aortic cusps result in complex flow patterns in the aortic root which may contribute to the risk of progressive dilation. Imaging these patterns with conventional echocardiography is challenging due to the angle dependency of colour Doppler. Blood speckle tracking (BST) is a novel method based on high-frame rate ultrasound that is less angle-independent and developed to evaluate complex flow. Purpose The aims of this study were to 1) describe and quantify flow patterns in the aortic root using blood speckle tracking and 2) quantitatively compare flow parameters (energy loss, vorticity, kinetic energy) between paediatric patients with BAVs and those with normal aortic valves. Methods Clinical and routine echocardiographic parameters were collected for children with normal and BAVs.  Children were imaged using a commercially available clinical scanner with research software enabling the acquisition of high-frame rate imaging and blood speckle tracking. Aortic root energy loss, vorticity and kinetic energy were measured in the parasternal long axis view. Results Data from 46 patients were analyzed (31 normal aortic valves, 15 BAVs) with no significant difference in age, height, weight or BSA between groups. Nine patients (60%) had right-left fusion; 6 (40%) had right-non fusion. Qualitative flow assessment in aortic root demonstrated disturbed flow in the BAV group (see figure) generally directed towards the non-fused cusp (i.e non coronary cusp in right-left fusion). Patients with a BAV had higher aortic valve peak velocity (2.1 m/s vs 0.9 m/s, p< 0.001);  aortic root systolic energy loss (4.29 mW/m vs 1.79 mW/m, p< 0. 001), vorticity (38.7 1/s vs 31.1 1/s, p< 0.01) and kinetic energy (34.5  mJ/m vs 24.5 mJ/m, p = 0.04) compared to those with normal aortic valves. Conclusion(s) Blood speckle tracking can demonstrate altered flow patterns in the aortic root in patients with BAV. These patients have increased energy losses, vorticity and kinetic energy when compared to age matched patients with normal aortic valves however the relationship of theses parameters to aortic root dilation remains to be demonstrated. Abstract Figure. Flow patterns (A-C) and analysis (D-F)